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8.B. - Page 56 <br /> 49 HYDROLOGY AND WATER QUALITY <br /> 4.9.1 Existing Setting <br /> 4.9.11 Flooding <br /> Redwood Creek is located adjacent to the southern and part of the western boundary of the project <br /> site. According to the Flood Insurance Rate Map (FIRM)prepared by the Federal Emergency <br /> Management Agency (FEMA) for the project area,the site is located within Zone B,which is defined <br /> as "Areas between limits of the 100-year and 500-year flood; or certain areas subject to 100-year <br /> flooding with average depths less than one (1) foot or where the contributing drainage area is less <br /> than one square mile; or areas protected by levees from the base flood."23 <br /> Inundation Hazards <br /> Redwood City is located adjacent to the Bay,but is outside the County of San Mateo Tsunami <br /> Evacuation Planning Area.24 The project site is not located within a dam failure inundation hazard <br /> zone.�s The adjacent Redwood Creek flows through a concrete drainage channel and the waterway is <br /> not a landslide hazard.26 The project site is not subject to inundation by seiche or mudflows nor is <br /> the project site located within an area that could be exposed to inundation from sea level rise.�' <br /> 4.9.1.2 Stormwater Drainage <br /> The Redwood City Public Works Services Department maintains the storm drainage system which <br /> serves the project site. Stormwater in Redwood City is conveyed into creeks, lined channels, storm <br /> drainage pipes and retention basins, all of which drain directly into San Francisco Bay. <br /> Approximately 21 percent of the project site is covered by impervious surfaces. <br /> 4.9.1.3 Groundwater <br /> Groundwater in the vicinity of the project site is first encountered at appro�mately 20 ft bgs. The <br /> project site is not a designated groundwater recharge area. <br /> 4.9.1.4 Water Quality <br /> Nonpoint Source Pollution Program <br /> In 1988 the State Water Resources Control Board(SWRCB) adopted the Nonpoint Source <br /> Management Plan in an effort to control nonpoint source pollution in California. In December 1999, <br /> the Plan was updated to comply with the requirements of Section 319 of the Clean Water Act and <br /> Section 6217 of the Coastal Zone Act Reauthorization Amendment of 1990. The Nonpoint Source <br /> Management Program requires individual permits to control discharge associated with construction <br /> 23 Federal Emergency Management Agency(FEMA). Flood Map Panel#060325001 SB. 1982. <br /> <htt�://msc.fema.�ov> Accessed June 29,2011. <br /> 24 County of San Mateo. Tsunami Inundation Maps. 2009. <br /> <http://www.conservation.ca.�ov/c�s/�eolo�ic hazards/Tsunami/InundationMaps/SanMateo/Pa�es/SanMateo.aspx> <br /> �s Redwood City General Plan. Figure PS-S: Dam Inundation Flood Hazards. <br /> 26 Confirmed by Earth Systems Pacific geotechnical engineers in letter,(dated September 12,2011)addressing City <br /> comments. <br /> �'San Francisco Conservation and Development Commission. Shoreline Areas Potentially E�osed to Sea Level <br /> Rise: Central South Bay. <http://www.bcdc.ca.�ov/plam�in�/climate_chan�e/maps/16_55/cbay south.pdfl <br /> Accessed November 30,2011. <br /> 1410 Valota Road Residential Project 44 Initial Study <br /> Redwood City January 2012 <br />